The initial objective of this protocol is to assemble a well-documented group of patients with confirmed diagnoses of the erythropoietic protoporphyrias, including autosomal recessive Erythropoietic Protoporphyria (EPP) and X-Linked Protoporphyria (XLP) for clinical, biochemical, and genetic studies. The long-term objectives are (1) to conduct a longitudinal investigation of the natural history, complications, and therapeutic outcomes in people with erythropoietic protoporphyria, (2) to systematically investigate the psychological effects of the erythropoietic protoporphyrias on children and adults, and (3) to investigate the correlation between the identified genotypes and the resulting clinical presentation, also determining the possible interaction of other genetic markers.